Process for recovering solvents from the preparation of polymers by aromatic nucleophilic substitution polycondensation

Abstract

The present application relates to a kind of aromatic nucleophilic substitution polycondensation reaction preparation polymer solvent recovery method and its application.The method includes the following steps: S1: the reaction product stream of aromatic nucleophilic substitution polycondensation reaction is carried out first solid-liquid separation, and solid phase insoluble and first liquid phase part are obtained;S2: the first liquid phase part is carried out solidification in the presence of water, and solidification product is obtained;S3: the solidification product is carried out second solid-liquid separation, and solid phase polymerization product and second liquid phase part are obtained;S4: water-absorbing agent is mixed with the second liquid phase part, and liquid separation is carried out, and organic phase is recycled, and the water-absorbing agent includes the solid phase insoluble obtained in step S1.The solvent recovery method of the present application not only can effectively recover the solvent in aromatic nucleophilic substitution polycondensation reaction preparation polymer, but also reduces the recovery cost.

Description

Technical Field

[0001] This invention relates to a solvent recovery method for preparing polymers via aromatic nucleophilic substitution polycondensation. Technical Background

[0002] Aromatic nucleophilic substitution condensation polymerization is an effective method for preparing polyaromatic (sulfide) ethers, esters, amines, and amides. Inorganic bases, as acid-binding agents, have advantages such as low cost and simple post-processing. Commonly used inorganic bases include sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate. Without exception, the use of these inorganic bases produces water, thus rendering them unusable in water-sensitive reaction systems, or requiring a water-generating step followed by water removal before polymerization to obtain polymers with sufficiently high molecular weights. Patent CN101580591B reports the use of anhydrous potassium phosphate as an acid-binding agent to prepare polyaromatic (sulfide) ethers, esters, amines, and amides via aromatic nucleophilic substitution condensation polymerization. Since potassium phosphate reacts with acid to produce potassium hydrogen phosphate, it both binds the acid and does not produce water; therefore, this invention eliminates the need for water separation processes and water-separating agents. However, potassium phosphate is used in larger quantities and is more expensive than potassium hydroxide and potassium carbonate, requiring recycling to ensure low costs.

[0003] High-boiling-point aprotic polar solvents can provide higher reaction temperatures and better solubility of reactants and polymerization products. Furthermore, most of these solvents are miscible with water, and residual solvents and inorganic salts can be removed by washing with deionized water in post-processing to obtain pure polymers. Therefore, these solvents are widely used in the preparation processes of polyaromatic (sulfide) ethers, esters, amines, and amides. Current distillation techniques can effectively recover these solvents, but the concentration of the raw water needs to be kept stable; the higher the concentration, the less water is distilled off, and the lower the recovery cost. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a solvent recovery method for polymers prepared by aromatic nucleophilic substitution polycondensation reactions. In this invention, potassium phosphate, potassium chloride, and excess potassium phosphate generated during the preparation of polyaromatic (sulfide) ethers, esters, amines, amides, and other polymers are used as a desiccant. These are added to an aqueous solution containing solvent as a desiccant. By separating the organic and aqueous phases, some water is removed, increasing the solvent content in the organic phase and achieving concentration. Simultaneously, the salt solution in the aqueous phase can be directly used to recover phosphates without further dissolving in water.

[0005] Therefore, a first aspect of the present invention provides a solvent recovery method for preparing polymers via aromatic nucleophilic substitution polycondensation reaction, comprising the following steps:

[0006] S1: The reaction product stream of the aromatic nucleophilic substitution polycondensation reaction is subjected to a first solid-liquid separation to obtain a solid insoluble matter and a first liquid phase;

[0007] S2: The first liquid phase is solidified in the presence of water to obtain a solidified product;

[0008] S3: The solidified product is subjected to a second solid-liquid separation to obtain a solid-phase polymerization product and a second liquid phase;

[0009] S4: Mix the absorbent with the second liquid phase portion, perform liquid-liquid separation, and recover the organic phase. The absorbent includes the solid insoluble matter obtained in step S1.

[0010] According to some embodiments of the present invention, the method further includes washing and drying the solid insoluble material obtained in step S1 before step S2, to obtain dried solid insoluble material and washing liquid. According to a preferred embodiment of the present invention, the first liquid phase portion is combined with the washing liquid and then solidified in step S2. According to some embodiments of the present invention, the washing is performed using an aprotic polar solvent. According to some specific embodiments of the present invention, the washing is performed using the same aprotic polar solvent as used in polycondensation reactions.

[0011] According to some embodiments of the present invention, the aromatic nucleophilic substitution polycondensation reaction comprises reacting a halogenated monomer with a second monomer selected from phenolic monomers, thiophenolic monomers, or amine monomers in the presence of an aprotic polar solvent and potassium phosphate.

[0012] According to some embodiments of the present invention, the reaction product stream includes a polymerization product, an aprotic polar solvent, and at least one selected from potassium hydrogen phosphate, potassium chloride, and potassium phosphate. In this invention, potassium phosphate is used as an acid-binding agent. During the preparation of polymers such as polyaromatic (sulfide) ethers, esters, amines, and amides via aromatic nucleophilic substitution polycondensation, potassium hydrogen phosphate, potassium chloride, and excess potassium phosphate are generated, as shown in the following formula:

[0013]

[0014] According to some embodiments of the present invention, the polymeric product includes at least one of polyaromatic ether, polyaromatic sulfide, polyaromatic ester, polyaromatic amine or polyaromatic amide.

[0015] According to some embodiments of the present invention, the aprotic polar solvent includes, but is not limited to, one or more of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), N-butylpyrrolidone (NBP), 1,3-dimethyl-2-imidazolinone (DMI), N,N-dimethylpropenylurea (DMPU), dimethyl sulfoxide (DMSO), sulfolane (SFL), diethylene glycol dimethyl ether (2EGDM), triethylene glycol dimethyl ether (3EGDM), tetraethylene glycol dimethyl ether (4EGDM), polyethylene glycol dimethyl ether (PEGDM), or hexamethylphosphoric triamine (HMPA).

[0016] According to some embodiments of the present invention, in step S4, the absorbent further includes at least one of potassium hydrogen phosphate, sodium hydrogen phosphate, potassium chloride, sodium chloride, potassium phosphate, sodium phosphate, potassium dihydrogen phosphate, sodium dihydrogen phosphate, calcium chloride, magnesium sulfate, or sodium sulfate.

[0017] According to some embodiments of this application, the water-absorbing agent used may be, in addition to a mixture of potassium hydrogen phosphate, potassium chloride, and excess potassium phosphate generated during the preparation of polymers such as polyaromatic (sulfide) ethers, esters, amines, and amides using potassium phosphate as an acid-binding agent, one of potassium hydrogen phosphate, sodium hydrogen phosphate, potassium chloride, sodium chloride, potassium phosphate, sodium phosphate, potassium dihydrogen phosphate, sodium dihydrogen phosphate, calcium chloride, magnesium sulfate, and sodium sulfate, or a mixture of two or three of these.

[0018] According to some embodiments of this application, in step S2, the mass ratio or volume ratio of the first liquid phase to water is 1:(5-50), for example, it can be 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, and any value between them. According to some embodiments of this application, in step S2, the mass ratio or volume ratio of the first liquid phase to water is 1:(10-30).

[0019] According to some embodiments of this application, in step S4, the ratio of the absorbent to the second liquid phase is (0.01-10) g:1 ml, for example, it can be 0.01 g:1 ml, 0.02 g:1 ml, 0.05 g:1 ml, 0.1 g:1 ml, 0.5 g:1 ml, 1 g:1 ml, 2 g:1 ml, 3 g:1 ml, 5 g:1 ml, 7.5 g:1 ml, 10 g:1 ml, and any value between them. According to some embodiments of this application, in step S4, the ratio of the absorbent to the second liquid phase is (0.01-3) g:1 ml.

[0020] According to some embodiments of this application, in step S1, the first solid-liquid separation is performed by filtration. According to some embodiments of this application, the conditions for the first solid-liquid separation include: a temperature of -20°C to 100°C and a time of 1 hour to 48 hours.

[0021] According to some embodiments of this application, in step S2, the curing conditions include: a temperature of 10°C to 110°C and a time of 12h to 48h.

[0022] According to some embodiments of this application, in step S3, the second solid-liquid separation is performed by filtration. According to some embodiments of this application, the conditions for the second solid-liquid separation include: a temperature of 0°C to 100°C and a time of 12 hours to 48 hours.

[0023] According to some embodiments of this application, in step S4, the liquid-liquid separation is performed using a separating funnel. According to some embodiments of this application, the conditions for liquid-liquid separation include: a temperature of 10°C to 50°C and a time of 0.5h to 8h.

[0024] According to some embodiments of the present invention, the representative structures of the halogenated monomers in the aromatic nucleophilic substitution condensation reaction are shown below, and may be one or a mixture of two or more of them:

[0025]

[0026]

[0027]

[0028]

[0029] According to some embodiments of the present invention, the representative structures of the (thio)phenol monomer or amine monomer in the aromatic nucleophilic substitution condensation reaction are shown below, and may be one or a mixture of two or more of them:

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037] A second aspect of the invention provides the application of the method according to the first aspect in the process of preparing polymers by aromatic nucleophilic substitution polycondensation.

[0038] The solvent recovery method of the present invention can not only effectively recover the solvent in the preparation of polymers by aromatic nucleophilic substitution polycondensation reaction, but also reduce the recovery cost and simplify the treatment of reaction by-products, thereby improving the overall benefits. Detailed Implementation

[0039] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0040] Example

[0041] A polymer was prepared by aromatic nucleophilic substitution polymerization in an aprotic polar solvent using halogenated monomers, (thio)phenols or amine monomers, and potassium phosphate as an acid-binding agent. After polymerization, the insoluble matter was filtered off and washed with solvent. The insoluble matter was then vacuum dried to obtain a complex salt containing dipotassium hydrogen phosphate, potassium chloride, and potassium phosphate. The filtrate and washings were combined, solidified in deionized water, and the polymer was filtered off to obtain aqueous solutions containing solvents of different concentrations. Different types and masses of single inorganic salts or complex salts were added to aqueous solutions of different types and concentrations of solvents, and the layering phenomenon was observed. After complete layering, the aqueous phase and organic phase were separated in a separatory funnel, weighed, and their volumes were measured. Specific examples are shown in Tables 1-8 below, in Examples 1-57.

[0042] Example 1-12: Layering Experiment of DMAC Aqueous Solution with Dipotassium Hydrogen Phosphate

[0043] Table 1. Concentration and Amount of K2HPO4-DMAC-H2O System Added

[0044]

[0045]

[0046] Note: The H2O content includes the water of crystallization in K2HPO4·3H2O.

[0047] Table 2. Changes in solvent concentration after layering in the K2HPO4-DMAC-H2O system.

[0048]

[0049] Examples 13-24: Layering Experiment of Potassium Phosphate on DMAC Aqueous Solution

[0050] Table 3. Changes in solvent concentration in the K3PO4-DMAC-H2O system during layering.

[0051]

[0052] Note: The total mass of the DMAC aqueous solution is 100g.

[0053] Examples 25-36: Layering Experiment of Potassium Phosphate in DMF Aqueous Solution

[0054] Table 4. Changes in solvent concentration after the K3PO4-DMF-H2O system separates into layers.

[0055]

[0056]

[0057] Note: The total mass of the DMF aqueous solution is 100g.

[0058] Examples 37-48: Layering Experiment of Potassium Phosphate with NMP Aqueous Solution

[0059] Table 5. Changes in solvent concentration after layering of the K3PO4-NMP-H2O system.

[0060]

[0061] Note: The total mass of the NMP aqueous solution is 100g.

[0062] Examples 49-51: Layering Experiment of Composite Salt on DMAC Aqueous Solution

[0063] Table 6. Changes in solvent concentration after layering in the K2HPO4-KCl-K3PO4-DMAC-H2O system.

[0064]

[0065] Note: The H2O content includes the water of crystallization in K2HPO4·3H2O.

[0066] Examples 52-54: Layering Experiment of Composite Salt on DMF Aqueous Solution

[0067] Table 7. Changes in solvent concentration after layering in the K2HPO4-KCl-K3PO4-DMF-H2O system.

[0068]

[0069]

[0070] Note: The H2O content includes the water of crystallization in K2HPO4·3H2O.

[0071] Examples 55-57: Layering Experiment of Composite Salt on NMP Aqueous Solution

[0072] Table 8. Changes in solvent concentration after the K2HPO4-KCl-K3PO4-NMP-H2O system separates into layers.

[0073]

[0074] Note: The H2O content includes the water of crystallization in K2HPO4·3H2O.

[0075] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A solvent recovery method for preparing polymers via aromatic nucleophilic substitution polycondensation, comprising the following steps: S1: The reaction product stream of the aromatic nucleophilic substitution polycondensation reaction is subjected to a first solid-liquid separation to obtain a solid insoluble matter and a first liquid phase; S2: The first liquid phase is solidified in the presence of water to obtain a solidified product; S3: The solidified product is subjected to a second solid-liquid separation to obtain a solid-phase polymerization product and a second liquid phase; S4: Mix the absorbent with the second liquid phase portion, perform liquid-liquid separation, and recover the organic phase. The absorbent includes the solid insoluble matter obtained in step S1. The aromatic nucleophilic substitution condensation reaction includes reacting a halogenated monomer with a second monomer selected from phenolic monomers, thiophenol monomers or amine monomers in the presence of an aprotic polar solvent and potassium phosphate. The reaction product stream includes polymerization products, aprotic polar solvents, and at least one selected from potassium hydrogen phosphate, potassium chloride, and potassium phosphate.

2. The method according to claim 1, characterized in that, The method further includes washing and drying the solid insoluble matter obtained in step S1 before step S2, to obtain dried solid insoluble matter and washing liquid.

3. The method according to claim 2, characterized in that, The first liquid phase is combined with the washing liquid and then cured in step S2.

4. The method according to claim 2, characterized in that, The washing process uses a nonprotic polar solvent.

5. The method according to claim 1, characterized in that, The polymer product includes at least one of polyaromatic ether, polyaromatic sulfide, polyaromatic ester, polyaromatic amine or polyaromatic amide.

6. The method according to claim 1, characterized in that, The aprotic polar solvent includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, N-ethylpyrrolidone, N-butylpyrrolidone, 1,3-dimethyl-2-imidazolinone, N,N-dimethylpropenylurea, dimethyl sulfoxide, sulfolane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, or hexamethylphosphoric triamine.

7. The method according to claim 1, characterized in that, In step S4, the absorbent further includes at least one of the following: potassium hydrogen phosphate, sodium hydrogen phosphate, potassium chloride, sodium chloride, potassium phosphate, sodium phosphate, potassium dihydrogen phosphate, sodium dihydrogen phosphate, calcium chloride, magnesium sulfate, or sodium sulfate.

8. The method according to claim 1, characterized in that, In step S2, the mass ratio or volume ratio of the first liquid phase to water is 1:(5-50); and / or In step S4, the ratio of the absorbent to the second liquid phase is (0.01-10) g: 1 ml.

9. The method according to claim 1, characterized in that, In step S2, the mass ratio or volume ratio of the first liquid phase to water is 1:(10-30).

10. The method according to claim 1, characterized in that, In step S4, the ratio of the absorbent to the second liquid phase is (0.01-3) g: 1 ml.

11. The method according to claim 1, characterized in that, In step S1, the first solid-liquid separation is performed by filtration; and / or Step S2, the curing conditions include: a temperature of 10°C to 110°C, and a time of 12 hours to 48 hours; and / or In step S3, the second solid-liquid separation is performed by filtration; and / or In step S4, the liquid separation is performed using a separating funnel.

12. The method according to claim 1, characterized in that, In step S1, the conditions for the first solid-liquid separation include: a temperature of -20°C to 100°C and a time of 1 hour to 48 hours.

13. The method according to claim 1, characterized in that, In step S3, the conditions for the second solid-liquid separation include: a temperature of 0°C to 100°C and a time of 12h to 48h.

14. The method according to claim 1, characterized in that, In step S4, the conditions for liquid-liquid separation include: a temperature of 10°C to 50°C and a time of 0.5h to 8h.

15. The application of the method according to any one of claims 1-14 in the process of preparing polymers by aromatic nucleophilic substitution polycondensation.

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